Former AIG Chairman and CEO Maurice Greenberg has agreed to sell most of the AIG shares under his control in a deal worth at least $US278.2 million ($303.1 million).

In a statement to the US Securities and Exchange Commission, Starr International has confirmed the sale of 10 million shares to UBS Securities.

Starr International is a former AIG investment entity which was taken over by Mr Greenberg and six other executives following his ousting from the company in 2005. Mr Greenberg remains Chairman and MD of Starr International.

Starr will offload the majority of about 14 million shares it holds in AIG with the first of four transactions due in three years, according to the statement.

The deal is known as a variable prepaid forward sale agreement, and protects the seller from volatility by applying certain thresholds around the AIG share price.

Under the terms of that agreement, major gains and losses from the stock accrue to the purchaser. Starr will receive $US278.2 million as an upfront payment.